The present invention relates to cooling systems for engines, particularly engines used in vehicles. It is well known that engines and some accessories in vehicles need to be maintained within certain temperature ranges of operation in order to operate effectively and efficiently, and there are numerous systems for accomplishing this in use today. These cooling systems include coolant circulation systems which are used for engines, automatic transmissions, and various accessories. Some of these systems involve the use of cooling fans which are used to pull or push air flow through heat exchangers, such as radiators, and over engines and other accessories in order to help cool them and/or to maintain them within certain temperature ranges of operation.
Many of these cooling fans utilize fluid coupling devices (“fan drives”) of the wet friction-type for driving the engine cooling fans. These fan drives result in substantial savings of engine horsepower and typically operate only in the engaged higher speed condition when cooling is needed. These fluid coupling devices have various configurations and applications.
The wet friction fan drives also generate significant heat themselves and various cooling systems have been used in attempts to maintain the operating temperatures of the fan drives within acceptable ranges. These cooling systems include the use of cooling fins on the outer housings, as well as circulation of cooling fluids through part of the fan drives. Although many of these cooling systems for the fluid coupling devices, have proven to be successful, efforts are continuously being made to improve cooling systems for these devices, particularly to increase the capacity of the clutches in their useful load conditions.
It thus is an object of the present invention to provide an improved cooling system for fluid coupling devices of particularly of the wet friction type. It is a further object of the present invention to enhance the capacity of wet friction-type clutches for thermal resistance in the useful load conditions.